contacts[i][firstName] 与 contacts[i].firstName 的区别在哪呢？

[Ccneedmoney]

Challenge Profile Lookup has an issue.
User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36.
Please describe how to reproduce this issue, and include links to screenshots if possible.

My code:

//初始化变量
var contacts = [
    {
        "firstName": "Akira",
        "lastName": "Laine",
        "number": "0543236543",
        "likes": ["Pizza", "Coding", "Brownie Points"]
    },
    {
        "firstName": "Harry",
        "lastName": "Potter",
        "number": "0994372684",
        "likes": ["Hogwarts", "Magic", "Hagrid"]
    },
    {
        "firstName": "Sherlock",
        "lastName": "Holmes",
        "number": "0487345643",
        "likes": ["Intriguing Cases", "Violin"]
    },
    {
        "firstName": "Kristian",
        "lastName": "Vos",
        "number": "unknown",
        "likes": ["Javascript", "Gaming", "Foxes"]
    }
];


function lookUp(firstName, prop){
// 请把你的代码写在这条注释以下
 for(var i=0;i<contacts.length;i++){
  //if(firstName == contacts[i][firstName]){   //使用此句时结果不通过
   if(firstName == contacts[i].firstName){      //使用此句时结果通过
     if(contacts[i].hasOwnProperty(prop)){ return contacts[i][prop];}
     else { return "No such property"; }  
   }  
 }
   return "No such contact";
  

// 请把你的代码写在这条注释以上
}

// 你可以修改这一行来测试你的代码
lookUp("Akira", "likes");

[S1ngS1ng]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects#Objects_and_properties

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors

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